Temperate Oceans

Herbivorous Green Sea Urchins are voracious predators on macroalgae in kelp forests. Without predators like sea otters to keep urchins in check, they will make quick work of any kelp and other algae around, creating a ecological shift from a very diverse kelp dominated system to a species-poor urchin barren.
Ogliuga Island, Western Aleutians, Alaska